1. Field of the Invention
The described invention relates to the field of optical circuits. In particular, the invention relates to an optical probe for testing an optical circuit.
2. Description of Related Art
Optical circuits include, but are not limited to, light sources, detectors and/or waveguides that provide such functions as splitting, coupling, combining, multiplexing, demultiplexing, and switching. Planar lightwave circuits (PLCs) are optical circuits that are manufactured and operate in the plane of a wafer. PLC technology is advantageous because it can be used to form many different types of optical devices, such as array waveguide grating (AWG) filters, optical add/drop (de)multiplexers, optical switches, monolithic, as well as hybrid opto-electronic integrated devices. Such devices formed with optical fibers would typically be much larger or would not be feasible at all. Further, PLC structures may be mass produced on a silicon wafer.
FIG. 1 is a schematic diagram that shows an example of the current way that planar waveguides 20, 22 are tested. Typically, a PLC wafer is diced and optical fibers, 10, 12 are mounted to the edge of a PLC die. Light is sent into the PLC structure 5 by light source, such as a laser, coupled to a first optical fiber 10, and a photodetector coupled to a second optical fiber 12 detects the power of light transmitted to it. A photodetector coupled to the second optical probe 12 will detect the power of light transmitted to it.
If the PLC works properly, then optical fibers are permanently attached to the PLC, and the PLC is put into a package. However, if the PLC does not work properly, the unit is discarded, and the time and effort to dice, fiber mount and to comprehensively test the device are wasted. Thus, a method of testing a planar lightwave circuit at the wafer level or before fiber attach is important.